Menthofuran (3,6-dimethyl-4,5,6,7-tetrahydrocoumarone) naturally occurs in the oil obtained from flower buds of the peppermint plant and exercises a great effect on the aroma of that oil. Because this effect has not been duplicated by any other compound, menthofuran is important in the formulation of certain synthesized essential oils, such as peppermint oil. However, menthofuran is an expensive compound of limited availability.
In the past the methods used to synthesize menthofuran have either required expensive or relatively unavailable raw materials, or have suffered from poor yields. One advantage of the present process over those previously suggested is that it utilizes the relatively available inexpensive isopulegol as the starting material. Another advantage of the present process is that the reaction sequence is free of significant competing reactions. A further advantage of the present process is that menthofuran is produced in good yield.